Carburetor



Mara 19, 1935.

G. A. WAHLMARK I 1,995,110

CARBURET'OR Filed Oct. 7, 1951 2 Sheets-Sheet 1' March 19, 1935. G. A. WAHLMARK 1,995,110 CARBURETOR Filed Got. 7, 1951 2 Sheets-Sheet 2 I3 7 m m M Q T J Y A W v: in

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Patented Mar. 19, I 4

{.UNITED s ATEsrAT Nr oFFlcEY Gunnar A. Wahl nark; Rockford, 111., assignor of 5 one-third'to Ernest J. Svenson and one-third.

. to Charles H. Rystrom. both of Rockford, Ill.

Application October 7-,19sl,;serialNo.56'z,s42

6"Claims. (c1.12s 119)' 7 r The invention relates generally to carburetors embodiment illustrated. The scope of the invenand more particularly to an improved carburetor tion will be pointed out in the appended claims. for internal combustion engines for motor ve-- In the form selected for purposes of disclosure, vhicles. the invention comprises generally a casing 10 5 The general object of the invention is to provide having a vertical passage 11 extending there- 5 a new and improved carburetor which is simple through With'thev intake at its upper end anda .inconstruction and efiicient inoperation so as fuel discharge means or member 12 positioned to secure the proper fuefr'nixture for the engine substantially centrally of the passage so that at all operating speeds and during acceleration. air is drawn downwardly past the discharge 10 Another object is to provide an'improved carorifices. An annular throttle member 13 is 1o buretorembodying an auxiliary accelerator mounted in the-passage'for movement from an mechanism having a combined manual and au: idling position such as illustrated in Fig. 1 to a tomatic movement arranged to increase the voluwide open position such as illustrated in Fig. 3,; metric capacity. of the. carburetor and thereby and is arranged to be actuated by means includquickly increase the speed of an engine. ing a lever 14 securedto a rock shaft 15. A fuel 15 Another object is to provide an improved arreservoir 16.is formed im one side'of the casing 'buretor embodying'means for supplying hunted. and is preferably provided with a suitable float quantities of fuel during idling and normal op- 17 an in cont/1'01 m hani ni, f r 61;? erating conditions, together with auxiliary means mp 0f the im disclosed in ,myp pp 20 for supplying added quantities of fuel when there tion e al 534,003, fi ed April 30, 1931. Fuel '20 is a demand on the. engine for increased power, .fromthis reservoir is arranged to pass to the fuel Further objects and dvanta s i11 o 3p: discharge means through intermediate. connectparent from the following. detailed description ing P 13, 0. 8. 6. t0 taken in connection with the accompanying drawpply th idling a o mal running 1 1. f 25 ings, in which: 1 the motor. An auxiliary fuel supply for acceler- 25 Fig.1 is a longitudinal central vertical section at p s s obtained by means of an c through a preferred form of the invention, the ti e nism co pr n generally a p on view being taken approximately along-the line cylinder device 25 (Fig: and an auxiliary 11 of Fig. 2; i. 1 fuel discharge means 26 (Figs. 1 and 3). In addi- '30 Fig. 2 is a plan view of the device illustrated in i n. i order .to'enable the mvtorto be operated 30- ig; 1, partly in section along the'li'ne 2- 2 of i i t r u t e full ra efof engine Fig. 1. I I speeds and still provide sufiicient fuel for acceler- Fig.3 is a transverse vertical section approxiation other conditions requiring m x mum i mately along the line 3 3 of Fi 2 power, the inventiomprovid'es means for increas- Fig. 4 is a fragmentary section along the line ing the fuel supply to thymain e discharge 35 a 4-4 of Fi 2, Y means 12 when such heavy power demands are x Fig. 5 is an enlarged-view of the main fuel dismaide upon the enginecharge means and throtfle In the form in figst0 5 0f the g 6 is a fragmentary perspective v on a drawingsthe casing 10 is adapted to be mounted q 40 reduced scale disclosing the preferred form of in all-upright Position and is arranged to have 40 .the invention installed in operative relation on s lower end connectsd mtak? mamfold an automobile engine of an engine so that all wlll be drawn in through Fig. 7 is a fragmentary section'througha modithe top and dqwnwa'rdly tmfough W Passage p fied form of the invention; past the fuel discharge meansv 12 wluch 1s mount- 4o .1 j ed centrally therein. The fuel discharge means 8 1s fragmentary section of part of the is secured to the upper end of a .stem 28 which cooling system of 'the engine shown in Fig. 6. v

While the invention'is susceptible of embodigcs gg gfi g fgz g a g gifi g gg fi ment {many dlfierent 1 a P P extends inwardly from the side wall of the cas- Y .the drawings and shall herein describe miietall i-ngfi The port 23 is formed in the t m 28 and .5 one Such embodlment, Wlth modlfica" at its lower end connects with the port 22 which tion thereof, with the understanding that the is formed n the arm 29, t t 22 beingin pr s n di lo e is to be "considered that turn connected with the fuel reservoir 16 by. .emplificati'on of the principles of the invention. means of the ports 18, 19, 20 and 21. Prefi and is not intended to limit the invention to the erably this fuel supply passage is formed with 55 a restricted portion of predetermined size for the purpose of limiting the quantity of fuel which may pass therethrough. As illustrated herein, adetachable plug is screw threaded into a recess in the casing 10 and has a central bore in its inner end forming the port 21. The port 20 extends radially between the port 21 and the port 19 which is herein shown to be annular in form and in communication with the port 18. The port 20 is preferably of a predetermined size so as to limit the quantity of fuel which may pass therethrough to the fuel discharge means.

In the exemplarytembodimentof the invention the discharge member 12 (Figs. 1, 3 and 5) has an inwardly tapering lower conical portion 32, a.somewhat cylindrical central portion 33 having an outward flare 34 adjacent the upper edge thereof, and an inwardly tapered or conical upper end 35. A cylindrical chamber 36 is formed centrally in the discharge member and a tube 37 extends downwardly through said chamber and into the upper end of the stem28. The upper end of the tube 3.7 is flared outwardly into engagement with the wall of the chamber 36 so as to provide an annular recess surrounding the tube, communication being established intermediate said recess and the interior of "the tube by means of a plurality of ports 38. A valve spaced relation to supply the fuel for idling purposes. Intermediate the ports 41 are provided,

a plurality of substantially larger radial ports 42 which communicate at their inner ends with the upper end of the stem 28 and at their outer.

ends at a level aboye the idling position of the annular orifice 45. Additional ports 43 are preferably provided discharging at even a higher level on the discharge member so as to be substantially ineffective at 'lowerengine speeds and effective at the higher speeds.

The throttle 13 is preferably hollowas illustrated in Figs. 1 and 3, and is annular in form and provided with an annular orifice 45 in its ide wall adjacent the upper end. orifice as so positioned that when the throttle is in its upper or idling position as illustrated in Figs. 1

and 5, the outer ends of the ports 42 are above said orifice and the outer ends'of the ports 41 communicate with said orificef The lower edge 46 of the orifice then engages the central portion of the discharge member 12 and the upper edge 4'? of the orifice cooperates with the discharge member to form a restricted annular intake passage 48 to the chamber 49 in the throttle. At its lower endthe throttle is provided with a plurality 'of apertures 50. The throttle is slidably mounted on the stem 28 by means of a member- 54 (Fig. 3) and is operable by means of the con- ,trol lever 14 (Fig. 1).

throttle is shaped or stream-lined so as to offer a minimum of resistance to the passage of air through the carburetor. The outer surface of the throttle cooperates with' a sleeve, 60 in the casing passage 11 to form, an outer Venturi passage 61 therebetween, and the inner surface of the throttle cooperates with theadjacent surface 32 of the discharge member 12 to form an inner Venturi passage therebetween. The throttle thus cooperates to form andcontrol two Venturi passages, the inner being very close to the main discharge ports so as to control the mixture forthe slower engine speeds. The outer venturi is away from the main discharge ports vacuum than existsin the passage 11. due to the fact'that the opening at 48 is larger than the apertures 50, a reduced suction is obtained on the orifices 41 at idling and the mixture is therefore sprayed out of the apertures into the main passage 11 where it is mixed with the additional air which passes around the throttle. When the throttle is opened slightly the suction on orifices 41 is increased, thereby" feeding more gasoline. This makes a very smooth running motor, when opening the throttle, and obtains an extremely efiicient mixing of the fuel and air for idling purposes.

The volumetric fuel capacity of the preferred form of the invention is normally limited by the port '20 in the fuel supply passage, but in order to increase the volumetric capacity of the carburetor for the purpose of quickly increasing the speed of the engine the invention provides an auxiliary accelerating means. This means is generally of the form disclosed in my prior application hereinbefore referred-to, although in the present embodiment certain improvements have been made which insure practically instantaneous injection of additional quantities of premixed fuel and air into the passage 11 in ad-' also after such manual movement to supply ad-' ditional quantities of pre mixed fuel to the passage 11.

'As illustrated in the drawings, a cylinder 65 is positioned with its lower portion in an annular recess 66 in a projecting portion 6'7 of the casing 10 and has mounted therein a piston 68. I This piston is operable manually in an upward direction by means of the right-hand 69 positioned intermediate the piston and lever. Thus when the-throttle 13 is lowered manually by turning therock shaft 15 for the purpose of increasing the speed of theengine, the piston 68 are preferably so designed that the spring is com-' pressed even when the motor is running at a end of the lever 14 (Fig. 1) and a coiled spring constant speed around and miles per hour. The throttle at 55 miles is open about one-third, andif the throttle is then fully opened, the'acceleration charge of fuel is as great as when the 5 throttle is opened from its idling position.

A conduit'll communicates at one end with the upper portion of the'cylinder 6? through a suitable fitting '12 and at its other end is connected to the upper portion 73 of an auxiliary fuel reservoir 74 formed in the casing 10. This fuel reservoir is positioned adjacent the main reservoir 16- and is connected thereto at itslower end by means of a port 75 (Fig. 4). A disk type of check valve 76 is herein illustrated intermediate the intake port '75 and the main portion of the reservoir for permitting fuel to flow into the auxiliary reservoir from the main reservoir andfor preventing return flow into the main reservoir.

The compressed air delivered by the conduit '71 is utilized for discharging additional quantities of fuel and air into the passage 11 for acceleratingthe engine quickly. As illustrated most clearly in Figs. 1 and 3, the means 26 for uti- 5 lizing the compressed air comprises an auxiliary discharge member 717 provided with a discharge ,orifice '78 which is connected by means of .a port 79 to a tube 80 which extends downwardly into the fuel. -It will be obv'iousthat the com-- pressed air entering the upper portion of the auxiliary fuel reservoir willincrease the pressure therein and force fuel'out through the tube 8.0,- port '79, and orifice 78. Preferably a port 81 is provided leading to a nozzle 82 in the auxiliary fuel discharge member so that some" of the compressed air may pass therethrough and mix with the fuel prior to its discharge In this way pre-mixed fuel and air are supplied by the-accelerating means..-

into the passage 11.

Thus when the leverv 14 is actuated to lower the throttle 13, the piston 68 compresses air in the cylinderf65 and forces it into the auxiliary reservoir 74.- Since'the coiled spring 69 is normally contracted due to the suction on the piston, the decrease suction 'as the motor accelerates permits the coiled spring to expand and continue thdmoveme'nt of the piston to a considerable extent beyond that of the throttle 13. In order to provide for a substantially 50 instantaneous operation of the auxiliary fuel discharge means, the necessary air is drawn in, during the downward movements of the piston 68, through a port 84 (Fig. 4) which is provided intermediate the upper portion of the'main fuel reservoir above the fuel level and the lower portion of the auxiliary reservoirbelow- 'the check valve 76. Air is drawn through this port and bubbles up through the fuel in the auxiliary,

fuel reservoir.

In present day' motor car dperationgit is de--.

sirable to obtain rapid acceleration at lowspeeds and still provide for vefficient operation and minimum fuel consumption at all speeds; In

' order to provide for eflicientfuel consumption at the higher operating speeds, the supply duct inmal operating conditions.

when the engine called upon to develop .relatively more powerfas in climbing hills at lower speeds. Under such conditions, if the motor is a limited to the fuel which will pass through the k restricted supply duct, the'necessary'power is not developed. The invention: therefore provides' a mechanism for supplyinga'dditional fuel to the main fuel discharge means under abnor- In the form illustrated herein, this means comprises a valve-controlled by-pass around the restricted port 20 of the main fuel passage, and as shown in Fig; 1, includes a port 85 communicatingat its-upper endwith the main fuel reservoir and at its lower end with an annular recess 86 formed in the plug 30. A port-8,7 in said plug connects said recess with the axially extending port 21 sothat fuel may pass' from the main reservoir into the port 22 in addition to that passing. through the port 20. For controlling the flow ofadditional fuel a valve 88 is formed on the lower end of a cylindrical stem 89 which is slidably mounted Within thefuel reservoir. At

its upper end this stem passes through a bore 90 I in a cover 91 of the reservoirand into a chamber 92 formed between said cover and a cap 93. The l valve ,stem 89 is-preferablyprovided with a collar 94 and a coiled spring 95 is positioned intermediate said collar andgone end of an adjustable bracket 96, so as normally to urge the stem up- .wardly and raise the valve 88 t6 open the port 85. The other end of the bracket 96 is secured to a screw device 9'7 so that the springtension tending to open the valve may be adjusted.

The upperend of the valve stem 89 is normally in'abutment with one end of a diaphragm 10o which is mounted within the chamber 92 and has itsother end-secured to the cap. 93. .-A suitable fitting 101 is provided for securing'the' diaphragm to the cap and has a port 102 extending-therethrough communicating with a conduit 1% through which a suitable fluid mayjbe conducted to the interior of the diaphragm for the purpose of closing the valve 88. In addition to this means for closing the valve against the action of the spring 95, there are preferably provided suitable passages between the chamber 92 and and passage 11 for the purpose of exhausting or vac'uumizingthe chamber 92 and in that way ex-' panding the diaphragm 100. As illustrated herewith .the. chamber 92 and. at its other end with an annular recess 105 .formed intermediate the casing 10 and the sleeve 60. This recess is connected with the passage 11 by means of ports 106 and. 10? extending through said sleeve, the port 107 preferably being positioned, as illustrated most clearly in Fig. 5-, so as to communicate with the passage ll above the throttle when it is in its idling position. The port 106 communicates with the passage 11 below the port 107.

It has been found with a certain make of auto mobile equipped'with the preferred form ofthe invention that the vacuum in the chamber 92 at a speed of 5 miles per hour is-a pproximately 4% inches of mercury and that itdecreases substantially uniformly so that at 55miles per hour the vacuum is 4 inchesfof mercury. Thereafter the vacuum decreases more rapidly so that at '75 miles it isonly 2 inch'es of mercury. .These mercury readings were obtained in the chamber 92 although at '5" miles per hour the suction in the main passage, 11 was approximately 21' inches.

of mercury, and at 75 miles per hour it was 1 inchesv of mercury. Since at '75 miles per hour a'passage' 104 (Fig 2) connects atone end.

the chamber92 it appeared thatat least a part of the vacuum in the chamber 92'was due to the aspirating effe'ctof the air passing over the ends of the ports 106 and 107. The spring 95 is normally adjusted so that the valve 88 will be closed when the vacuum in the chamber 92 is equal to or greater than 4 inches of mercury.

Since the vacuum in said chamber falls off rapidly at the higher speeds, means is preferably provided for maintaining the valve in its closed position at such speeds." A's disclosed herein, this is accomplished by subjecting the interior of the diaphragm 100 to a pressure and preferably a variable pressure which builds up as the speed of the engine increases. For example, the conduit 103 may be connected to the water manifold 110 of an engine 111, as illustrated in Figs. 6 and 8, so as to subject the diaphragm to the water pressure. The engine is provided with a water pump 112 'driv'enby the engine throughthe fan shaft 113, the intake of the pump being connected to the lower part of a radiator 114 by' a conduit 115. The outlet of the pump was connected directly to the water jacket of the engine.

The outlet of the water manifold is connected to the upper end of the'radiator by means of a fitting 116 and a. conduit117. The water pressure in the installation under consideration was found to be approximately of a pound per square inch at 30 miles per hour, of a pound per square inch at 55 miles per hour, and 1.08 pounds per square-inch at 75 miles per hour.

'A pressure of 1.08 pounds per-square inch was suflicient to close the valve 88 approximately half way without any vacuum in the chamber 92.

- By this arrangement, it will be evident, the preslation in the engine. Thus when the engine is cold and this valve is closed, there is no pressure within the diaphragm 100, the valve 88 then remaining open and supplying fuel for a richer mixture.

In operation, when increased power demands are placed on the engine, the suction in the passage 11, in inches of mercury, drops to a marked extent. It is under conditions such as this that the vacuum in the chamber 92 also. drops with the result that the valve 88 is opened so as toadmit additional quantitiesoffuel to the main -fuel discharge means and enable the eng ne to deliver the increased power demanded. In adapting the invention foruse with different types of engines and for providing various operatingcharacteristics of the engines, the coiled spring 69 provided in the auxiliary accelerating mechanism may be varied to a considerable extent.both as to length and strength. In some types of v installations it has been found that a maximum expansion of or of an." inch is adequate. When such is the case there is not any great danger of the carburetor becoming."fiooded when the engine is stopped. It is to be understood. that when the engine stops there, is no suction on the underside of the piston 68 to keep the coiled spring contracted with the result that the spring expands.

accelerating purposes, a coiled spring may be pro- However, when .it is dev sired to give the piston 68 a greater stroke for the suction in the as age 11 was below that in vided capable of expanding to a much greater extent. When this is done, means is preferably provided to prevent flooding of the carburetor when the engine is stopped.

.One formof such a means is illustrated in the modified form of the invention shown in Fig. 7. In this. form a coiled spring 120 is arranged to give the piston 68 a much longer movement, for example 1%; inches, when the suction in the recess '70 drops. would ordinarily occur during the accelerating movements of the throttle but it will also be apparent that it would'occur when the engine is stopped. As illustrated in Fig. 7; a conduit 121 is This movement of the piston 10 connected at its upper end to the fitting 72 so 15 as to be in communication with the upper end of the cylinder 65 and at its lower end said conduit communicates with a chamber 122' formed in the casing 10 beneath the recess "70. This chamber may be exhausted through a port 123, the exhaust 20 being controlled by means of a valve 124 slidably mounted in the casing and normally held in its openv position when the throttle is in its idling position. For thispurpose a stem 125 on the valve passes into the recess 70 and into engage 25 ment with the lever 14. In this way, when the engine is shut off, the pressure due to the rise of the piston 68 is relieved through the conduit, 121. When, however, the throttle 13 is lowered to increase the speed .of the engine, the-valve '30 124 is closed by means of a coiled spring 126 so that the pressure in the upper end ofthe cylinder, 65 'is available for accelerating purposes.

A screw device 127 is preferably threaded in the lower end of thecasing' beneath the right-hand end of the lever 14. (Fig. 1) to facilitate the adjustment of the idling position of the throttle. Inthe form of the invention disclosed in Fig. 7, this screw device is arranged to engage the lower surface of the valve 124 and acts through the ing purposes. 'In its preferred form this means is illustrated as comprising an annular member or ring 130 of arcuate cross section having a? pluralityof apertures 131 therein. This ring is secured to a supporting sleeve 132 by means of a plurality of arms 133, the sleeve being slidably mounted 'on a stern 134 .which extends upwardly from the discharge member 12'and is secured at. its upper end to a'bracket 135 attached to the, upper end ofthe casing by suitable screws 136.

lower end for attachment to the, discharge mem ber and has the valve 39 secured thereto so that .by inserting 'a suitable tool in a slot 13'! provided in the upper end of the stem said valve This stem is preferably screw'th'readed at its v may be adjusted from the exterior of the carburetor. The ring 130 is arranged to be moved from an inoperative or raised position, as illustrated in Fig. 3,'to an operative or lower position, as illustrated in Fig. 5, by means including a lever 138 (Fig. 3) which is pivotally mounted ends said lever is suitably connected to the sleeve 132.

The ring 130 is preferably arcuate in cross section, as illustrated most clearly in Fig. 5, and

when the ring is in its position to restrict the passage 11 the outer'ed'ge of the ring is in'abutment withthe sleeve 60 and the inner edge of the ring is spaced a slight distance .from thedisannular passage therebetween. Thus the choke device restricts the flow of air and directs the air so that it is effectively mixed with the fuel drawn from the discharge ports in the'member 12. In

improves the .efiiciency and. the accelerating mechanism provides additional fuel for increasing the power during acceleration. The provision of a by-pass port around the restricted pororder to prevent flooding of the carburetor an added quantities of fuel when the power demands annular check valve member 141 is provided which normally closes the apertures 131 in the ring 130 and is secured in its closed position by means of a coiled spring"142. Thus if the operator neglects to raise the choke device after the engine has started and sufficient suction is established to overcome the action of the spring 142 the annular checkwalve is drawn downwardly to enlarge the effective openingthrough the passage 11 and increase the quantity of air passing therethrough.

The invention not only provides a carburetor capable of supplying the necessary quantities of fuel to an engine under all operating conditions, but also embodies improved means for thoroughly xing the fuel and air prior to its passage to the engine so as to utilize to the fullest extent .the 51' added fuel supplied for accelerating and also for 1'25 will be apparent by referr' g to Fig. 5 that when meeting the load requirem nts at low speeds. It

the throttle is in its idling position the fuel is supplied through the tube 37 and ducts 47, air being drawn in through the port 40 and down through the upper end of the tube 37, then out through the ports 38 and the annular recess formed in the chamber 36 to the ports 4'7. Thus the fuel and air is first mixed within the annular recess portion of thechamber 36 and this mixture then passes through the ports 4'1, and as it passes into the hollow throttle is mixed with additional air drawn through theannular orifice 48. Furthermore this fuel mixture then passes down through the hollow throttle andis sprayed out through the ports 50 in a completely atomized condition. As the throttle is lowered for the pur-. pose of increasing the engine speed, this flow of fuel through the. channels just described continues and is augmented by additional fuel which is supplied through the ports 42 and mixed with air as it passes through the annular orifice 48. For idling and in the lowr range of engine speeds the fuel is mixed in the hollow throttle and then sprayed out of the ports 50 after which it. is mixed with additional quantities of air which pass around the throttle through the venturi 61. The means for thus completely. mixing the fuel and air is extremely eflicient and is readily effective to mix with air the added quantities of fuel whichare supplied to the discharge member when the valve 88 is opened. For this reason-in actual installations it has been found that a carburetor which will increase the mileage per gallery of gasoline to a marked. extent over other devices 'will at the same time provide a phenomenal pick-up and will so effectively mix the fuel and air that a car may be driven up grades at less than five miles per hour.

It will be apparent that .by providing-a restricted portion in the main fuel 'isupply passagewaythe efliciency of the carburetor is incrased during normal operatingconditions and particularly at the higher engine speeds and that by providing means forsupplying quantities of premixed fuel andair for accelerating purposes the capacity "of the carburetor is greatly increased by this means only during the accelerating periods. The restricted portion-in the main fuel supply passageway provides a relatively lean mixture for continuous running conditions and thereby with a close fit.

on the engine are increased permits the fuel supplied ,for normal running conditions to be out down to a minimum, since it will be evident that whenever additional fuel is required it is immediately available through the by-pass. As

disclosed herein, the means for controllingthe .valve for the by-pass operates automatically to supply added quantities of fuelin the lower speed ranges when the power demands on the engine 45 increase, so that the by-passed fuel is available not only for increased load conditions; while running at a uniform speed, but is also effective to supplyadditional fuel to the discharge member v for accelerating purposes.- Furthermore the means for controlling the by-pass valve is efiec- I 68 and. cylinder 65 which are preferably provided The lower conical portion 32 of the discharge member preferably tapers very gradually so that This provides automatic lubrication for piston 3 when the throttle is lowered from the idling position, as shown in Fig. 5, the inner Venturi passage controls accurately and with'aprecision-like degree the increase of fuel and air passing through the carburetor. This gradual increase in the size of theinner Venturi cooperates with the other features of the device to use the fuel efliciently.

I claim as my invention:

1. A carburetor comprising, in combination; a casing having a passage therethrough, fuel discharge meafis positioned to discharge into said passage, a-fuel reservoir, a passageway intermediate said reservoir and discharge means having a restricted portiondetermining the normal volumetric. capacity ,of the carburetor, a throttle for controlling the supply of fuel and air through said passage, and means for supplying added quantities of fuel to said discharge means when theload on the engine increases at the lower speeds comprising a by-pass from said reservoir 'around: the restricted portion of said passage, a. valve controlling the flow of additional fuel through said by-pass, means operable by the suction in said passage normally holding said valve closed; resilient means arranged to open the valve when said suction drops below a predetermined amount, and means including pressure producing means driven by the engine effective at, higherengine speeds to partially close'said valve.

2.-A carburetor comprising. in combination, a-

casing having a passage therethrough, fuel discharge means positioned inlsaid passage, a fuel reservoir, a passageway intermediate said reservoir and discharge means, a throttle for,con-

trolling the supply of fuel'and air through said 'tion of the main supply passageway for supplying through, fuel discharge means positioned substan tially centrally of said passage, a fuel reservoir, a passageway intermediate said-reservoir and discharge means having a restricted portion determining the normal ,volumetric capacity of the carburetor, a throttle for controlling the supply of fuel and air through said passage, and means for supplying added quantities of fuel when the load on the engine increases at the lower speeds comprising an auxiliary supply port, a valve controlling the fiow of additional fuel through said port, means operable by the passage of air through said passage normally holding said valve closed, resilient means arranged to open the valve when said suction drops below a predetermined amount, and means operable at the higher engine speeds to partially close said valve.

4. -A carburetor having, in combination, a casing with a passage extending therethrough, fuel. discharge means positioned to discharge into said passage; a throttle for controlling the flow of fuel a and air through said passage, a fuel reservoir, a fuel supply passageway connecting said reservoir to said discharge means, and means for supplying added quantities of fuel to said passage when the loadon the engine increases at the lower oppansible bellows device, a chamber in which said device is positioned, and means for exhausting said chamber to expand said device and close said valve comprising a duct communicating at one end with the chamber and at its other end with said passage, and means for supplying fluid to the interior of said bellows device including pressure producing means driven by the engine.

5.A carburetor having, in combination, a casing with a passage extending therethrough, fuel discharge means positioned in said passage, a throttle movable longitudinally of ,said passage for controlling the flow of fuel and air therethrough, a fuel reservoir, a fuel supply passageway connecting said reservoir to said discharge means, and means for supplying added'quantities of fuel to said discharge means when the load on the engine increases at the lower operating spe'eds comprising an auxiliary supply port, a valve for controlling the inlet of fuel to said port,

means tending to hold said valve open, and means for closing said valve comprising an expansible bellows device, a chamber in which said device is positioned, means for exhausting said chamber to expand said device and close said valve comprising a duct communicating at one end with the chamber and at its other end. with said pas sage, and means for supplying a pressure fluid to the interior of said bellows device including pressure producing means driven by the engine.

6. In combination, a water cooled engine having a cooling chamber connected at its opposite ends to a radiator, a pump in said connections for circulating the water, a thermostatic valve controlling the fiow of water from said chamber to the radiator and which closes at a predetermined low temperature to prevent circulation, a carburetor for supplying fuel and air to the engine, a main fuel supply means in said carburetor, an auxiliary fuel supply means for said carburetor, means for shutting off said auxiliary fuel supply means including a device responsive to the pressure in said circulating system, and a connection to said system on the radiator side. of said thermostatic valve so that when'the engine is cold said auxiliary fuel supply means is effective.

\ GUNNAR A. WAHLMARK. 

